We do this in order to make best use of reading periods. In the last week, two authors have yanked material from under us because they had been accepted elsewhere. While that is wonderful news for the author, it does not allow us to make best use of the limited time we have. Why should we spend time reading a submission if it is only going to be withdrawn?
Here is a little reminder of our submission policy:
Simultaneous submissions are NOT okay. Please do not send us multiple submissions -- please only send us one story at a time and do not send your next submission until we give you a reply to the first. Reprints are OK, but discouraged. If you submit a reprint, we will look at it provided it has not been published within twelve months and the author currently bears the copyright. A short bio would be nice, including any awards or published credits, however your story will stand on its own merit.
If you absolutely, positively MUST send a sim-sub PLEASE just tell us.